Topic: Front Brakes Will Not Bleed. Why?

[L8KRFAN]

Decided to refresh the front end brakes on my 79 T/A. Purchased a new (not reman) M/C from Pep Boys (made in China of course), purchased new rubber hoses from Napa (also made in China, ughhh!), and purchased new hard lines from Classic Industries (Major PITA to install). After all is said and done, I can't get the fronts to bleed. I get fluid to the calipers but now matter how many times my assistant (wife) pushed the pedal then held, when I cracked the bleeder, could not get a fluid stream.

Any ideas? Could I have gotten a bad master? I do seem to see a leak of fluid from between where the m/c seats into the booster. Help!

[Grand73Am]

If you're getting fluid to the calipers, it would seem the master is working. Try removing a bleeder completely to see if fluid will come out of the caliper hole.

I once had a bleeder that didn't have the hole drilled in the side of it, so it wouldn't bleed. So, that's something else to check. 

You may not be leaking behind the master. Maybe it's just some fluid that spilled out the rear chamber, since the master angle is pretty steep.

[oldskoolubr]

Is this a 2 or 4 wheel disc?  There is a valve in the center of the prop valve that sometimes can be a pain!  Did you bench bleed the master?

[joe d]

also open the lid on te master, then open both left and right front bleeders and let gravity bleed, as oldschool said, did you bleed the master first? if not then start with that as your new pita hard lines are airated

[Wallington]

If using the pedal to pump up and bleed the system you shouldn't need to touch the proportioning valve, it's for pressure system bleeding.

[joe d]

If using the pedal to pump up and bleed the system you shouldn't need to touch the proportioning valve, it's for pressure system bleeding.

unless they bottomed out and tripped the valve

[Wallington]

you mean due to operating with low/no fluid or a fault of sorts?

[joe d]

most depress the brake pedal all the way to th floor when bleeding with a helper and sometimes when depressed all the way will trip the proportioning valve and will have to be reset, when depressing all the way with a worn master cylinder it will flip the seal as well

[L8KRFAN]

To answer a few questions:

Remove bleeders. Yes, did that plus removed the caliper and blew some air into where the banjo bolt/hose mounts as well as the bleeder location just in case there was any crap in there. Didn't seem to help. When I would remove the lines I would get fluid dripping from the lines so fluid is getting there. Just had problem building pressure to the fronts when pedal bleeding.

Bench bleed. Yes, as I alwasys do. It did seem to take forever of plunging the piston and tapping the m/c body to take out I think all the air.

Gravity bleed. Yes, first the rears and they were great, constant drip drip drip of fluid on both sides. Then did a quick pedal bleed a few times and got good squirt and I thought all was good until I moved to the fronts. Fronts too time to get fluid there but again could not get pressure to the fronts. When I would crack open the bleeder (after wife giving four pumps), not much fluid would come out and wife said pedal would not sink.

The situation is the same on both fronts so that tells me it's something above, perhaps the master or prop valve. You guy agree? I think I'm going to take back the master and get another one. They're cheap, only about $40 new. At least start there. Also, how do I reset the prop valve?

It took me most of Saturday and half of Sunday to do all this. I was so tired and frustrated to the laughing point. Lol!

[oldskoolubr]

If using the pedal to pump up and bleed the system you shouldn't need to touch the proportioning valve, it's for pressure system bleeding.

unless they bottomed out and tripped the valve

Thats what I was thinking Joe that it trips when you disassemble or when even just replacing you need that little tool Right?

[joe d]

should be a nipple on prop valve that you have to push back in, but have to relieve the pressure to do so, if you can get the pedal to depress all the way it will reset itself but assistant has to stop as soon as she feels the click and hold it there whilst you close the bleeeder

[joe d]

do you have line clamps? if so then clamp off the front hoses and see if you have a pedal, remove the clamps one at a time while assistant holds pressure on the pedal and see if you get a pedal drop, you may have bad hoses. why did you replace calipers? many replace calipers due to seized front brakes when in fact it is a hose

[Wallington]

I'm still having troubles with mine too but have given up until someone else can help out. I've bled the brakes several times after new lines, booster, mc, and rebuilt callipers. There are no air bubbles at all, just fresh fluid coming through. The wheels spin with only slight resistance after bleeding, but pump the pedal once or twice and usually find that one front wheel has locked up and the other very firm. Repeat the process, they free up and think it's sorted, touch pedal after bleeding and they don't release again. I tried driving around the yard while working brake pedal, there's still pressure there. One rear drum felt a little warm after a few laps but it could just need adjusting rather than the same issue.

[joe d]

aus78, if you press the pedal and the fronts lock up, then crack the bleeder and see if the pressure releases, if so yo have bad front hoses

[L8KRFAN]

An update to my brake problem... The "new" m/c I purchased is definitely leaking. A drop of fluid will build up and eventually drip. I have another m/c on order from Summit, it's Bendix 11944, also a new unit. The first m/c is the Pro Stop brand from Pep Boys. Hopefully the Bendix performs better than the Pro Stop brand.

I found the button on the prop valve but can't seem to get it to depress for the life of me! Tried my finger, screwdriver, etc... I might just buy a new prop valve from inlitetube.com. They cost about $85.

We'll see how it goes this weeknd when I install the new m/c. This is all frustrating as hell! All I want to do is drive my T/A.